1. Field of the Invention
The present invention relates to a mold-pressing apparatus.
2. Description of the Prior Art
As is well known, conventional mold-pressing apparatuses are widely used for in a variety of industrial applications in many fields. Each mold-pressing apparatus loads molding material like resin powder or ceramic powder, for example, in the cavity between the upper and lower molds and eventually molds the powder material into the predetermined shape by pressing and heating it in the mold.
Conventionally, mold-pressing apparatuses are widely used for manufacturing electric elements such as photoelectric conversion elements or integrated circuits. The mold of any conventional mold-pressing apparatus is composed of the upper and lower molds and is arranged so that the lower mold can be moved towards the upper mold, or conversely, the lower mold is fixed so that the upper mold can be moved toward the lower mold.
When operating any conventional mold pressing apparatus, resin powder material is applied between the upper and lower molds during the preliminary pressing process. Then the powder material is pressed and heated by the upper and lower molds. Finally the molded piece is extracted from the molded position between the upper and lower molds.
Conventionally, an oil-pressure-applied mechanism or pneumatic mechanism or a combination of these is used for driving the molding press. More particularly, an oil pressurized radial pump is used for example. Using the servo motor for controlling the output of pressurized oil from the radial pump per unit time, pressurized oil output from the radial pump is fed to the oil-pressure-applied piston for driving the pressing mold. When the pressurized mold is closed, in other words, when oil pressure is applied, pressure is intensified by decreasing the volume of pressurized oil output from the radial pump. It is possible for the pressing mold to accelerate the speed of applying pressure before and after executing the pressing operation by increasing the volume of pressurized oil output from the radial pump. The radial pump can continuously vary the volume of output oil from the positive to the negative range. The radial pump can switch the output and the intake of the pressurized oil. As a result, the clearance between the molds of the pressing mold can be fixed by reducing the volume of pressurized oil output from the radial pump. This allows the mold operator to easily adjust the stroke and pressing time of the pressing mold. In particular, the ease of adjusting the pressing time is extremely important for the molding press which simultaneously applies pressing and heating processes.